Baseball Rules - What Didn't You Know?

I've been watching baseball for a long time. More than 20 years. You would think in that span of in-person games, games on TV, and Joe Morgan's explanation of the rules every Sunday night (okay, maybe not the last one), I would have seen it all, and had a pretty good grasp on the rules of baseball, even the obscure ones. After all, surely I have seen almost everything in my lifetime, right?

Remember the "You Make The Call" commercials, where you got to decide--sometimes based on little known rules--what the correct call should be? I would have earned a big fat fail on Sunday night.

The Phillies were playing the Brewers in the game. It was the top of the eighth inning. Two outs. Runners on first and third. Utley is the batter. He strikes out on a wild pitch. With a runner on first base; Utley should be out; inning over, right? Right?

Not so right. The runner from third scored, the runner from first moved to second, and Utley was safe on first base. In my head, this is wrong! First base is occupied; the batter is out! There aren't a lot of times in a baseball game where I am totally, completely lost, and can't explain the action on the field, but this was one of those times.

Until I looked up the rule.

I wasn't completely wrong. The "uncaught third strike" rule (where the batter can run to first base if the ball is not caught) does have the limitation of a runner on first base, but this rule does not apply with two outs. 

From Wikipedia:

On an uncaught third strike with no runner on first base (or with two outs, regardless of whether there is a runner on first), the batter immediately becomes a runner. The strike is called, but the umpire does not call the batter out. The umpire may also actively signal that there is "no catch" of the pitch. The batter may then attempt to reach first base, and must be tagged or thrown  out.

And now you know.

Any other rules that you should know but one day found out you didn't? Have you ever been totally lost at a call in a baseball game, and you had to have it explained? Please tell me I'm not the only one. What is the hardest rule for you to understand? What rule should be removed from baseball?

The A's try to split the series with a win today.